Storage stable polyolefin compatible non-crosslinking size for fiber glass strands

ABSTRACT

Continuous glass fiber with a polyolefin compatible sizing composed of a coupling agent, a stabilizer, a lubricant, a non-crosslinking film forming polymer, softening agent and surfactant are disclosed for utilization in polyolefin polymer reinforcement. The article formed and formation method for fiber combination with a polyolefin polymer are also disclosed.

This is a continuation of application Ser. No. 191,792, filed Sept. 29,1980, abandoned, which is a division of application Ser. No. 935,275,filed Aug. 21, 1978, which issued Feb. 3, 1981 under U.S. Pat. No.4,248,935.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to glass fiber strand treatment andparticularly relates to treating glass fibers during or after formingwith an aqueous sizing which prepares the glass fibers for bonding topolyolefins in the reinforcement of polyolefin materials and further haslong shelf life and can be used from forming packages formed immediatelyinto mat.

2. Description of the Prior Art

It is known that glass fibers in the form of continuous strands, choppedstrands or mats can be used successfully to reinforce polyolefins. Andit is known that without effective coupling between the glass and thepolyolefin, the adhesion between the two will be weak and separationwill occur under shear or tensile stresses. It is further known that theaffinity of glass for water aggravates bond weakness when glass isinadequately bonded to polyolefins.

A workable method has been disclosed which permits bonding glass to"lower" polyolefins which are essentially crystalline plastics formedfrom monomers having three or more carbon atoms. As disclosed in U.S.Pat. No. 3,013,915 at column 2, lines 38-46, glass bonding topolyolefins may be improved by "cleaning the glass surface, applying acoupling agent to it, treating with a chemical agent which is a sourceof dehydrogenating or oxidizing radicals, contacting the polyolefin withthe glass, and fusing it by heating the polyolefin above its meltingpoint to complete the interbonding." At column 4, lines 16-19, thedisclosure reveals a preference for radical sources having lowdecomposition points below 180° F. and at column 4, lines 69-71,indicates that exposure to heat must be avoided.

U.S. Pat. No. 3,849,148 proposes the method of sizing fiber glassstrands with an aqueous sizing containing a coupling agent, a heatstable organic peroxide, a non-ionic surfactant and a lubricant. Thisprocess was successful in giving some storage capability to the sizedstrands but did not result in long storage life and further remainssusceptible to degradation by high storage temperatures.

U.S. Pat. No. 3,882,068 discloses the sizing composition for glassfibers in several plastic resin systems wherein the size comprises acoupling agent and a polyolefin emulsion.

U.S. Pat. No. 3,437,550 discloses a method of increasing the bonding ofglass fibers to polyolefins by treating the fiber with a crystallinepolypropylene matrix polymer. The preferred modifiers disclosed aremaleic anhydride and acrylic acid.

U.S. Pat. No. 3,883,333 discloses a method and apparatus for forming acontinuous glass fiber mat or sized fibers that are suitable for bondingwith polyolefins. The process and apparatus disclosed allows lay down ofthe fibers to form a mat immediately after formation of sized strands.

While the above processes and compositions were useful, there remains aneed in the art for a sizing to promote the binding of polyolefins tocontinuous glass fiber strands with increased adhesion. Further, thereremains a need for a sizing for glass fiber strands which will allow theformation of the sized fiber into forming packages or mat that may bestored indefinitely prior to use. Effective sizings containing peroxideshave limited shelf-life since they are very sensitive to elevatedtemperature variations during drying of the fibers and high temperaturesduring storage which can cause premature degradation of the peroxidesthus reducing the effectiveness of the sizing in binding the glass fiberstrands to the polypropylene matrix. A problem in forming the fiber matwith continuous lay down after strand formation is that the sizingmaterials readily cross-link and form deposits on the sizing applicatorequipment. These deposits cause delays in production and defects in themat that is being formed. Therefore there is a continuing need for animproved sizing for continuous lay down mat formation.

SUMMARY OF THE INVENTION

It is an object of this invention to overcome the disadvantages of theprior processes and compositions.

It is an additional object to provide an improved sizing for continuousformation of a storage stable mat that will bind with polyolefins.

It is a further object of this invention to provide a storage stablepolyolefin bonding sizing for continuous glass fibers.

It is a further object of this invention to provide a storage stablepolyolefin bonding sizing for continuous glass fibers.

It is another object of this invention to produce polyolefin glass fibercomposites using glass fibers from forming packages.

It is further an additional object to produce storage stable formingpackages of glass fiber strands.

It is another object to create a polyolefin bonding sizing notsusceptible to thermal degradation during the drying operation.

It is another additional object to form a sizing that does not createdeposits on the sizing applicator equipment.

These and other objects of the invention are generally accomplished byapplying a sizing comprising a coupling agent, a stabilizer, alubricant, a non-crosslinkable film-former, a softener, a surfactant andan aqueous carrier to a glass fiber strand. The sized strand is thenwound into a forming package and dried for later use as a reinforcementfor polypropylene material.

In a preferred embodiment of the invention, an aqueous sizing comprisinga coupling agent of gamma-amino-propyltriethoxysilane, a lubricantcomprising cis-butenedioic acid, a lubricant of an emulsion ofmalenoated amorphous polypropylene, a non-crosslinkable film-former ofvinyl acetate homopolymer, a softener of polyethylene and a surfactantare supplied in an aqueous sizing to a glass fiber so as to impregnatethe strand and improve its ability to reinforce polypropylene articles.The strand is immediately formed into a mat, needled and dried to removethe aqueous carrier. The dried mat is combined with polypropylene sheetand under heat and pressure formed into a fiber reinforced article.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The utilization of the sizing system of the instant invention results innumerous advantages over the prior processes. The utilization of astorage stable sizing with no shelf-life limitation improves productioncapability because it allows the storing and distribution of mat orforming packages of sized glass fiber strand. Prior to the instantinvention, it was necessary that the sized fiber mat be used shortlyafter forming or be immediately formed into composite articles. Further,the drying of the sized fiber was difficult as the drying temperatureconditions were limited by a necessity to not decompose the peroxide, animportant ingredient of the sizing. With utilization of the instantsystem, it is possible to form mat or forming packages of sized glassfiber strands at a central location. These may be then shipped withoutlimitation as to temperature or atmosphere during shipping to distantpoints for fabrication into composite polyolefin glass fiber reinforcedarticles. This offers considerable improvement since the forming ofglass strands no longer must be carried out at the same location thatthe polyolefin glass fiber reinforced article is formed. Thus as can beseen that although the individual ingredients had been used in othersizings, the instant combination of ingredients allows the achievementof numerous advantages not present in prior systems. Another advantageof the instant system is that the sizing contains no cross-linkablematerial to build up on the applicator devices and therefore is cleanerrunning. Further as the sizing does not cross-link it has a long potlife.

Any glass suitable for reinforcing and for drawing in fiber form maysuitably be treated in accordance with the present invention. Soda-limeglasses and borosilicate ("E") glasses are particularly suited for thispractice.

The glass fiber strands to be treated according to this invention may betypically produced according to the teachings of U.S. Pat. No.2,133,238. The glass fiber strands are composed of a multitude of fineglass filaments which are formed by being drawn at a high rate of speedfrom molten cones of glass located at the tips of small orifices in abushing. During formation, the filaments are coated with the aqueoussizing prepared according to the description below. Coating of thefilaments takes place while they are moving at a speed of the order of1,000 to 20,000 feet per minute. The coating is accomplished in theimmediate vicinity of the hot bushings and the glass furnace in whichthe glass is melted, and after coating, the glass fiber strands move ashort distance onto a collecting means. After the strands have beensized, they may be dried to drive off residual moisture from the sizedglass.

The aqueous sizing to contact and coat the glass fiber strand iscomposed of a coupling agent, a stabilizer, a softening agent, asurfactant, a lubricant and a non-crosslinkable film former.

The coupling agent may be any interfacial boundary area adhesivecompound which acts to unite the surface of the glass fiber strand withthe polyolefin polymer. Among typical coupling agents for uniting glassfiber strand and polymers are metal salts of the strong metal acids suchas basic chromium chloride, basic chromium sulfide having a trivalentmetal ion selected from the group consisting of chromium, cobalt,nickel, copper, and lead having at least one hydroxyl group attached tothe metal and at least one anion of a strong mineral acid attached tothe metal; Werner type complexes in which a trivalent nuclear atom suchas chromium is coordinated with an organic acid such as methacrylicacid, for instance, methacrylic acid complex of chromic chloride, andother Werner type coupling agents, having vinyl, alkyl, amino, epoxy,mercapto, thioalkyl, thioalkyl and phenol groups. Suitable forutilization in the instant invention are coupling agents from the silaneand siloxane groups. Typical of such coupling agents are hydrolyzable,vinyl, allyl, beta-chloropropyl, phenyl, thio-alkyl, thio-alkaryl,amino-alkyl, methacrylato, epoxy, and mercapto silanes their hydrolysisproducts and polymers of hydrolysis products and mixtures of any ofthese. A preferred coupling agent is gamma-aminopropyltriethoxysilane asthis material has been found to provide very good coupling between theglass fiber strand and polyolefin polymers at low concentrations andwith good stability.

Any stabilizer may be selected which acts as a secondary coupler toimprove the stability of the sizing system, assists in crosslinking,improves the coupling agent to fiber interface and assists the action ofthe silane in coupling. Typical of stabilizers for sizes suitable forthe instant invention are ethylenically unsaturated carboxylic acid oranhydrides. Examples of such difunctional acids and anhydrides includemaleic acid, fumaric acid, itaconic acid, citraconic acid, acrylic acid,methacrylic acid, crotonic acid, icocrotonic acid, mesaconic acid,angelic acid, maleic anhydride, itaconic anhydride and citraconicanhydride, and mixtures thereof. A preferred stabilizer is maleic acid(cis-butenedioic acid) that gives a stable system and improves thecoupling action of the silane coupling agent.

Any material that acts as a lubricant to aid film forming and assist thecoupling may be used as the lubricant of the invention. Suitablelubricants are chemically modified polypropylenes. Maleonated or acrylicmodified polypropylenes are preferred as they result in a sized fiberwith good storage properties and ability to feed from the formingpackage.

The polymer which forms the non-crosslinkable film former material ofthe sizing of the system of the instant invention may be any materialthat provides strand integrity to aid in the processability of the glassfiber strand allowing strand removal from a forming package. Thenon-crosslinkable polymer provides the desired level of plasticity tothe size such that the sized fiber of the instant system has an extendedshelf-life and also the processability to allow successful needling of amat formed of the sized fibers of the instant invention. Thenon-crosslinkable polymer generally is a homopolymer, or mixtures ofhomopolymers, or fully cured polymer that will not crosslink in theconditions of the sizing and molding operations to which the sized fiberis subjected in the drying of the aqueous sizing from the fiber andmolding with a olefin homopolymer such as polypropylene. Typical ofnon-crosslinkable film-forming polymers suitable for the instantinvention are epoxies, polyesters, polyurethanes, polyvinyl acetates,polyvinyl alcohols and acrylics. A preferred non-crosslinkablefilm-forming material is vinyl acetate homo-polymer as vinyl acetatehomopolymers are low in cost, do not degrade at the instant formingtemperatures, and provide good strand integrity when used on a glassfiber strand.

The sized glass fibers may be formed and the size applied by the knownmethods of fiber formation and sizing application. Representative of amethod of fiber formation and sizing application is the processillustrated in FIG. 2 of U.S. Pat. No. 3,849,148 which is herebyincorporated by reference. Glass fiber filaments emerge from orifices ofan electrically heated bushing. These fibers are attenuated and by meansof a strand pulling device these filaments are gathered to form a strandof glass fiber which may comprise numerous individual fibers. The sizingis applied to the fibers by a conventional size applicator such as akiss-roll applicator or a belt applicator device. Detail of a sizingapplicator is shown in U.S. Pat. No. 2,728,972. The filaments afterexiting the bushing are cooled by air or preferably water. The filamentsare gathered into bundles by a gathering shoe and are then led to astrand pulling device such as illustrated in U.S. Pat. No. 3,292,013 aswell as in the above referenced, U.S. Pat. No. 3,849,148. The glassfiber strand or strands, if the filaments exiting from the bushing havebeen separated into several strands, are then wound onto a forming tubeon a collet rotating at approximately 7,500 rpm to produce a strandtravel of approximately 12,000 to 15,000 feet per minute. The glassfiber strand forming packages are then dried. This generally isaccomplished by baking the packages of fiber at a temperature and for alength of time sufficient to remove substantially all of the water.Generally a curing time for the instant size is about 11 hours at 270°F. After drying the forming tube may be removed resulting in a formingpackage of sized glass fiber. These forming packages may be storedvirtually indefinitely when sized with the instant sizing. When theforming package is desired for use in forming a polyolefin compositearticle, a group of the forming packages are arranged so that thestrands may be drawn from the packages and laid down to form a mat offibers such as disclosed in U.S. Pat. Nos. 3,883,333 or 3,664,909. Themat is then needled and combined or impregnated with polyolefin resin orlaminated with polyolefin sheets to form reinforced polyolefin articleswhich are heated at a temperature in the range of 400° F. to about 430°F. at a pressure of about 9250 pounds per square inch for about 5 toabout 20 minutes to bind the sized glass fibers of the invention to thepolyolefin. The laminated polyolefin glass fiber mat articles may thenbe stamped or molded by a variety of means, including that of U.S. Pat.No. 3,664,909 hereby incorporated by reference, to produce reinforcedpolyolefin laminates suitable for use as containers, automobile seats orfor other low-cost, high strength and low temperature uses.

The coupling agent may be utilized in amounts which results in goodinterfacial boundary area adhesion between the glass fiber strand andthe polyolefin. A silane coupling agent concentration of about 2 toabout 30 percent silane by weight of the solids in the sizing emulsionhas been found to be suitable. A preferred percent has been found to beabout 5 to about 12 percent of the silane to give maximum adhesion withminimum cost.

A lubricant may be utilized in any amount which results in goodstability of the sizing system. A suitable amount of lubricant has beenfound to be about 10 to about 50 percent by weight of solids in thesizing solution for good forming and fabrication processability.

A stabilizer may be used in any amount which results in good interfacebonding of the film-forming materials to the glass fiber strand. Asuitable amount has been found to be about 1 to about 15 percent byweight stabilizer to the solids of the sizing emulsion. A preferredamount of stabilizer has been found to be about one-half the amount ofthe coupling agent to give good adhesion of the film formers to thecoupling agent.

The non-crosslinkable film forming material is utilized in an amount togive the desired handling properties to the sized strand. Thenon-crosslinkable polymer imparts plasticity to the fiber. The filmformer acts to provide integrity to the glass fiber strand so that itdoes not come apart into filaments during processing or cuttingoperations. A normal range of the non-crosslinkable polymer would bebetween about 20 and about 60 percent by weight of the solids in thesizing emulsion. A preferred amount of the non-crosslinkable polymer isbetween about 35 and about 40 percent by weight to give optimumhandleability.

The softener may be any material that softens the strand, modifiesdrape, decreases the scroopyness of the fibers and contributes lubricitysuch that the fibers may be successfully needled in the mat withoutexcess fiber breakage. The preferred softeners are the polyethyleneiminederivatives such as disclosed in U.S. Pat. No. 3,597,265 as they givegood drape and result in a mat that needles well.

The surfactant of the invention acts as a wetting agent, emulsifier anddetergent to maintain the sizing as an emulsion and prevent build up ofthe solids on the applicator apparatus. Among suitable surfactants arecondensates formed by condensing propylene oxide and propylene glycolsuch as those disclosed in U.S. Pat. No. 2,674,619. The preferredsurfactants are those condensates having a molecular weight of about1500 to 2000 and between 70 and 80 percent by weight of thepoly(oxyethylene) in the molecule to successfully control foaming andaid in stabilizing the sizing emulsion. The surfactant is utilized inany amount that effectively maintains the emulsion and prevents build-upof solids on the applicator. A suitable amount is about 0.1 to about 5percent by weight of the solids component of the sizing.

The softener may be utilized in any amount that softens the fiber forgood needling. A suitable amount has been found to be between about 0.2and about 1 percent by weight of the solids in sizing emulsion.

The sizing emulsion generally contains between about 99 percent andabout 80 percent water. It is preferred in the use of a kiss rollapplicator to have between about 92 and 96 parts by weight water in thesizing solution. Thus, solids amount is dependent on the applicator thatis used to size the fiber strand.

The sized fiber forming packages and sized mat of the instant system maybe utilized to reinforce any polymeric resin article. However, theinstant fibers find greater functionality in the reinforcement ofpolyolefinic resin polymers such as polyethylene, 5-methylpentene and2-methylpentene. A preferred polyolefinic polymer for utilization withthe instant sized glass fiber strand is polypropylene since this polymerbinds very well with the instant sizing, is relatively low cost andgives good strength properties when glass reinforced. The ratio ofpolypropylene to glass may be selected in any ratio that gives thedesired properties to the finished article. Generally a ratio of about10 to about 50 percent glass by weight is suitable. A preferred amountis about 30 to about 45 percent by weight glass in the molded article togive a good balance of cost properties and structural strength.

The amount of the sizings used on the glass may be any amount whichresults in good structural strength of the finished polyolefin fibercomposite, good fiber integrity and handleability. A suitable amount ofsizing is about 0.02 to about 1 percent by weight sizing solids to totalweight of the sized strand of glass. A preferred range is about 0.6percent to give good fiber integrity and handleability and binding withpolypropylene.

The following Examples are preferred embodiments of the instantinvention. The parts and percentages are by weight unless otherwiseindicated.

EXAMPLE I

    __________________________________________________________________________    Ingredient                   Active Ingredient                                Functional Identification                                                                 Chemical Identification                                                                        Parts by Weight                                  __________________________________________________________________________    Coupling agent                                                                            gamma-aminopropyltriethoxy-                                                                    11                                                           silane                                                                        Union Carbide A-1100)                                             Stabilizer  cis-butenedioic acid                                                                           11                                               Lubricant   emulsion of maleonated                                                                         32                                                           amorphous polypropylene                                                       22% active                                                                    10% surfactant and KOH                                                        68% water                                                                     surfactant = alkoxylated                                                      phenol                                                            Non-crosslinkable film                                                                    vinylacetate homopolymer                                                                       43                                               former      emulsion                                                                      54% solids                                                                    (National Starch Resyn 25-1031)                                   Softener    polyethylenimene 3                                                            (Emerylube 6717 Emery Industries)                                 Surfactant  condensate of    .5                                                           propylene oxide and                                                           propylene glycol                                                              (Pluronic F-68)                                                               BASF Wyandotte Corp.                                              __________________________________________________________________________

The above mixture is combined with deionized water to give an emulsionof about 4.5 parts solids.

The glass fiber strand sizing is prepared by adding most of thenecessary deionized water to the mix tank and then slowly adding thelubricant and surfactant to the mix tank as it is agitated. The couplingagent is then added to the mix tank followed by adding the maleic acidwith continued agitation. After the addition of the maleic acid,stirring is carried out for about 20 minutes to dissolve the acid. Thenthe non-crosslinkable film-forming material and softener is added to thetank. Additional necessary make-up water is added and the batch ischecked to determine that the specifications are within the range ofabout a pH of 6 and a solids of about 4.5 parts per hundred.

In a preferred embodiment, the aqueous sizing mixture is applied tofiber filaments that are formed from a 400-hole bushing. The filamentsare treated by a kiss roll applicator to coat about 0.6 percent solidsby weight of the glass onto the filaments. The filaments are split intofour strands and directly utilized to form, as in U.S. Pat. Nos.3,883,333, a continuous fiber mat which is then needled. The needled matis then dried via use of infrared heaters to flash-off residualmoisture. The dried, needled mat is laminated with polypropylene polymerin the weight of about 60 parts by weight of polypropylene polymer to 40parts by weight of the needled mat. The polyolefin resin and mat arecombined via a temperature range of about 400° F. at a pressure of about90 pounds per square inch for about 5 minutes to bond the reinforcingglass fibers to the polyolefin. The heating is carried out betweenstainless steel belts. The laminate of sized fiber matting andpolypropylene is then stamped into a tub such as described at column 6through 7 of U.S. Pat. No. 3,849,148 and tested for structural strengthand structural modulus. The flexural strength was found to be about23,000 pounds per square inch and the flexural modulus about 1×10⁶pounds per square inch. This example shows that the polypropylenereinforcing sized glass fiber strands of the instant invention providesatisfactory strong reinforced articles without the use of a peroxide orcross-linking resin.

EXAMPLE II

The method of Example I is repeated except the strands of fiber glassare wound to form forming packages that are dried at about 270° F. for11 hours. The forming packages are used after three months of storage toform mat which is needled and combined with polypropylene polymer as inExample I. The flexural strength is found to be about the same as inExample I. This illustrates that the sizing of the invention provides astorage stable strand with good adhesion properties to polypropylene.

EXAMPLE III

The method of Example I is repeated except that 15 parts by weightN-beta(aminoethyl)gamma-aminopropyltrimethoxysilane (Union CarbideA-1120) is substituted for the silane of Example I. The sized fiberproduct displays good physical properties and successfully adheres tothe polypropylene resins.

EXAMPLE IV

The method of Example I is repeated using the following compositionsizing:

    __________________________________________________________________________    Ingredient                   Active Ingredient                                Functional Identification                                                                 Chemical Identification                                                                        Parts by Weight                                  __________________________________________________________________________    Coupling agent                                                                            gamma-aminopropyltriethoxy                                                                     5                                                            silane                                                                        (Union Carbide A-1100)                                            Stabilizer  cis-butenedioic acid                                                                           2.5                                              Lubricant   emulsion of maleonated                                                                         38                                                           amorphous polypropylene                                                       22% active                                                                    10% surfactant and KOH                                                        68% water                                                                     surfactant = alkoxylated                                                      phenol                                                            Non-crosslinkable film                                                                    vinylacetate homopolymer                                                                       50                                               former      emulsion                                                                      54% solids                                                                    (National Starch Resyn 25-1031)                                   Softener    polyethylenimine polymer                                                                       4                                                            (Emerylube 6717 Emery Industries)                                 Surfactant  condensate of    .6                                                           propylene oxide and                                                           propylene glycol                                                              (Pluronic F-68)                                                               BASF Wyandotte Corp.                                              __________________________________________________________________________

The above mixture is combined wit deionized water to give an emulsion ofabout 4.5 parts solids.

The fibers made with the above sizing are utilized to produce goodcomposite articles when combined as in Example I with polypropylene.

EXAMPLE V

The method Example I is repeated with the following sizing:

    __________________________________________________________________________    Ingredient                     Active Ingredient                              Functional Identification                                                                 Chemical Identification                                                                          Parts by Weight                                __________________________________________________________________________    Coupling agent                                                                            amino-functional silane                                                                          24                                                          ##STR1##                                                                     (Union Carbide Y-5162)                                            Stabilizer  cis-butenedioic acid                                                                             12                                             Lubricant   emulsion of maleonated                                                                           32                                                         amorphous polypropylene                                                       22% active                                                                    10% surfactant and KOH                                                        68% water                                                                     surfactant = alkoxylated                                                      phenol                                                            Non-crosslinkable film                                                                    vinylacetate homopolymer                                                                         34                                             former      emulsion                                                                      54% solids                                                                    (National Starch Resyn 25-1031)                                   Softener    polyethylenimine   2                                                          (Emerylube 6717 Emery Industries)                                 Surfactant  condensate of      .5                                                         propylene oxide and                                                           propylene glycol                                                              (Pluronic F-68)                                                               BASF Wyandotte Corp.                                              __________________________________________________________________________

The above mixture is combined with deionized water to give an aqueousemulsion of about 4.5 parts solids, formed and tested as in Example Iwith successful results.

While the invention has been described with reference to severalembodiments, those skilled in the art will recognize that variations maybe made to the described methods and devices without departing from thesubstance of this invention. For instance, a pigment or dye could beadded to the sizing solution without interference with its effect.

As will be apparent to those skilled in the art, the present system maybe modified and equivalent elements or processes may be employed incombination therewith without departing from the spirit of theinvention. For instance, an application device for the sizing could beutilized which would not require as large an amount of water in thesizing emulsion. Further, the fiber forming packages of the instantinvention may be utilized in the reinforcing of polymeric materialsother than polyolefins. Also, a combination of the sized fiber formingpackages of this invention could be utilized with fibers sized with adifferent material, with unsized fibers or with chopped fibers sizedwith the instant sizing.

Thus, the present disclosure of preferred embodiments is not intended tolimit the scope of the applicant's invention.

I claim:
 1. An aqueous sizing composition to provide storage, stableglass fiber strands, consisting essentially of: coupling agents,surfactant, softener, ethylenically unsaturated carboxylic acid oranhydride stabilizer in an amount of about 1 to about 15 percent byweight of the solids of the sizing composition, a maleonated or acrylicmodified polypropylene lubricant, and a non-crosslinkable homopolymerfilm forming polymer selected from the group consisting of epoxies,polyesters, polyurethanes, polyvinyl acetates, polyvinyl alcohols andacrylics, and water in an amount of about 80 to about 99 percent of theaqueous composition.
 2. The aqueous sizing composition of claim 1,wherein said coupling agent is selected from the group consisting ofsilanes and siloxanes.
 3. The aqueous sizing composition of claim 1,wherein said coupling agent is an aminosilane.
 4. The aqueous sizingcomposition of claim 1, wherein said coupling agent comprises betweenabout 2 and about 30 percent by weight of the solids of the aqueoussizing, said stabilizer comprises between about 1 and about 15 percentby weight of the solids of said sizing, said maleonated or acrylicmodified polypropylene lubricant comprises between 10 and about 50percent by weight of the solids of said sizing, said non-crosslinkablepolymer comprises between about 20 and 60 percent of the solids of saidsizing, said softener comprises between about 0.2 to about 1 percent ofthe solids of said sizing, and said surfactant comprises between about0.1 and about 5 percent by weight of the solids of said sizing, andwater comprises about 80 to about 99 percent by weight of said sizing.5. The aqueous sizing composition of claim 1, wherein said couplingagent comprises between about 5 and about 12 percent of the solids ofsaid sizing, said stabilizer comprises between about 2.5 to about 6percent of the solids of said sizing, said lubricant comprises betweenabout 10 and about 50 percent by weight of the solids of said sizing,said non-crosslinkable polymer comprises between about 35 and about 40percent by weight of the solids of said sizing, said softener comprisesbetween 0.2 and about 1 percent by weight of the solids of said sizing,and said surfactant comprises between 0.1 and about 5 percent of thesolids of said sizing and water comprises about 92 to 96 parts by weightof said sizing.
 6. The aqueous sizing composition of claim 1, whereinsaid softener is selected from the group consisting of polyethyleniminederivatives.
 7. The aqueous sizing composition of claim 1, wherein saidsurfactant is selected from the group consisting of condensates ofpropylene oxide and propylene glycol.
 8. The aqueous sizing compositionof claim 1, wherein said ethylenically unsaturated carboxylic acidstabilizer is cis-butenedioic acid or anhydride.